1. Field of Invention
The present invention relates to produce bags with draw tops and having side walls of differing type synthetic resin materials, more specifically one of the side walls being of a synthetic resin film and the other side wall being of a synthetic resin fiber mesh.
2. Description of the Prior Art
Composite bags formed of one synthetic resin mesh sheet and one synthetic resin film sheet have been proposed. So far as is known, however, the two sheets have been joined together along a common inner seam formed between the two walls at a bag bottom on or near the bottom portions of the sheets. The common inner seam was thus located to form the bottom of the contents holding portion of the bag. However, with this structure, problems have arisen, particularly with relatively large or comparatively heavy items such as potatoes or other produce. The weight and impact of these types of items as they were introduced during bag filling were received directly onto the seam joining the bag wall sheets together. Problems with breakage or rupture of the seams have occurred because of this. Further, bag filling operations have been disrupted and products for filling the bags spilled or wasted.
Wicket produce bags have been developed for automatic produce packing machines. One portion of the bag has holes formed in it so that the bags can be suspended from wickets or pegs on an automatic packing machine. The earliest such bags were of polyethylene film. Machines and methods for forming produce bags of a synthetic resin fabric mesh have been recently developed by the assignee of the present application, for example as described in co-pending U.S. patent application Ser. No. 08/888,175, filed Jul. 3, 1997, now U.S. Pat. No. 6,080,093. These bags were formed of a synthetic resin fabric mesh, such as the woven fabric of cross-laminated synthetic resin fibers known as Cross Laminated Airy Fabric or (CLAF(copyright)) from Atlanta Nisseki CLAF, Inc. This fabric is an open mesh material of cross-laminated warp and weft strands or fibers of synthetic resin.
These types of bags are particularly useful for produce that must have access to fresh air to preserve the shelf life of the produce. However, when wicket holes are formed in this type of fabric mesh for automatic produce bag filling or packing machine purposes, problems have been found to occur. Slits were formed in the mesh in the area of the wicket holes leading away from the holes. The slits were formed in order to aid in tearing of the bag away from the packing machine once the bag was filled with product.
When the fabric mesh was slit for this purpose near the wicket holes, only a certain number of synthetic resin fiber strands in the fiber mesh were left uncut. The remaining uncut fiber strands were the sole support for the bag when it was suspended from the wicket rods or pegs and being filled with product. The number of strands left uncut was variable and indeterminate, and the reliability of the bags for use in automatic packing machines suffered. Bags with too many strands cut did not have adequate strength for use and would fall from the wickets during filling operations. Faulty bags could slow up operation of automatic packing machines by falling from the wickets when being filled with produce.
Produce bags of certain types have been provided with draw strings or cords in their tops. So far as is known, the prior produce bags with draw strings or cords have been formed from bag material of either woven or knitted mesh. These have been desirable, for end users or purchasers are provided with a built-in closure mechanism permitting the bag to be re-closed after some of its contents were removed. The drawstring or draw cord also provided a lifting or carrying grip.
Another type of produce bag which has been available is a bag formed with both side walls of a synthetic resin film material. So far as is known, these bags are planned to be disposable. For this reason, the cost of producing a drawstring in this type of bag has made use of a drawstring undesirable. Another problem has been that there are, so far as is known, no satisfactory machines for making a bag of this type with a drawstring.
Briefly, the present invention provides a new and improved composite synthetic resin bag with a draw top to accommodate a draw member in it. The bag is formed of first and second side walls which are joined together along a bottom portion and two side edges. One of the side walls is formed from a cross-laminated synthetic resin fiber material mesh, such as a CLAF(copyright) material or the like, and the other side wall is formed of a synthetic resin film, such as polypropylene or polyethylene or the like. The wall of mesh material preferably forms a back or rear wall of the bag when placed on wicket pins of the equipment for product filling. The film wall preferably serves as the front or forward wall.
A first draw sleeve extends laterally along an upper portion of the first side wall of the bag, and a second draw sleeve extends laterally along an upper portion of the second side wall of the bag. Each of the draw sleeves has a draw member mounted in it. The draw member may be a band, strip, web, cord, string or the like. A slot is formed in each of the first and second draw sleeves for access by a user of the bag to the draw member.
The synthetic resin fiber mesh bag wall extends downwardly a certain predetermined length, but slightly less than the entire length of a completed bag. The film bag wall extends over a front face portion of the entire length of a completed bag and in addition has a further downward extension. When the bag is assembled, the downward extension is folded upwardly against an outer surface of the fiber mesh rear bag wall. The fiber mesh bag wall and the upwardly folded film wall extension are joined together at a seam spaced upwardly from the folded synthetic resin film bottom portion. The bag when assembled thus has a bottom portion which is formed entirely of a folded portion of synthetic resin film. The resin film has been found to be more elastic and thus resistant to impact and weight of produce as they enter the bag during packing.
It has been found that the fold of synthetic resin film exhibits greater strength during bag packing. Further, the seam between the fiber mesh wall and the film wall is spaced upwardly from the bottom of the bag and thus not directly subject to impact and weight of the product as it enters the bag during packing. An improved top corner seal structure is provided where the reinforcing strip and the front and rear side walls are joined. Bags according to the present invention exhibit greater strength in use during packing operations and are thus more reliable. Waste and damage to produce as a result of bags splitting at their bottom seams, either during loading or subsequent handling, are reduced with bags according to the present invention.
Bags according to the present invention are also adapted for use in bag-filling machines with wicket pins. In these cases, the fiber mesh side wall of the bag has a reinforcing strip of synthetic resin film extending along an upper edge above the draw sleeve. A wicket top is formed in the reinforcing strip for mounting the bag on the wicket pins of the bag packing machine or equipment.